I have recently been playing around with Gnome as my new desktop. My two primary Gnome based VMs are Fedora and Manjaro. I have Parallels Tools installed on both, but Coherence mode only works on the Fedora VM. On my Manjaro VM, the Parallels Coherence extension (under gnome tweaks) has a warning sign which when you hover your mouse over it says "Error loading extension" with no further details. I much prefer Manjaro to Fedora, so I am looking for any help getting Coherence mode up and running on my Manjaro VM. I have created fresh installs of both, and upon reboot of Fedora after installing tools, coherence mode is up and running. No such luck on Manjaro.
When I took that screenshot I was running Manjaro 17.10, I am now running 18.0 and still have the same issue.